1. Field of the Invention
The present invention relates to an implantable drug delivery device for infusing a therapeutic agent into an organism, and more particularly, relates to an improved orientation of the motor assembly and pumphead assembly of an implantable drug delivery device, providing a low profile.
2. Description of the Related Art
Implantable drug infusion devices are well known in the art. These devices typically include a medication reservoir within a generally cylindrical housing. Some form of fluid flow control is also provided to control or regulate the flow of fluid medication from the reservoir to the outlet of the device for delivery of the medication to the desired location in a body, usually through a catheter. These devices are used to provide patients with a variable and prolonged dosage or infusion of a drug or other therapeutic agent.
Active drug infusion devices feature a pump or a metering system to deliver the drug into the patient""s system. An example of such a drug infusion pump currently available is the Medtronic SynchroMed programmable pump. Additionally, U.S. Pat. Nos. 4,692,147 (Duggan), 5,840,069 (Robinson), and 6,036,459 (Robinson), each assigned to Medtronic, Inc., Minneapolis, Minn., and each of which disclose a body-implantable electronic drug administration device comprising a peristaltic (roller) pump for metering a measured amount of drug in response to an electronic pulse generated by control circuitry associated within the device. These patents are incorporated herein by reference in their entirety. Such pumps typically include a drug reservoir, a fill port, a peristaltic pump having a motor and a pumphead to pump out the drug from the reservoir, and a catheter port to transport the drug from the reservoir via the pump to a patient""s anatomy. The drug reservoir, fill port, peristaltic pump, and catheter port are generally held in a housing, or bulkhead. The bulkhead typically has a series of passages extending from the drug reservoir and through the peristaltic pump that lead to the catheter port, which is typically located on the side of the housing.
The prior art delivery devices, however, are limiting in that they are relatively large. When a relatively large drug delivery device is implanted in a patient""s body, the patient is obviously well aware of its presence and may, as a result, suffer considerable discomfort and anxiety. Additionally, large implantable devices are difficult to implant in children and small adults and require larger surgical incisions. Other problems can arise from the use of large implantable devices, including skin erosion.
In prior art implantable drug infusion devices, the bulkhead includes a pump chamber. A motor and corresponding drive assembly for operating the pump are positioned directly above the pump. One serious disadvantage of this configuration is the height of these devices. For example, the motor/pumphead in the SynchroMed device has an overall height of approximately 10.7 mm. Because implantable devices are typically implanted subcutaneously and may be implanted in a patient for many years, it has always been an objective in the design of such devices that they be as small and lightweight as possible. Size and weight are critical factors with respect to the physical and psychological comfort of the patient. Thus, it is desirable to provide an implantable drug infusion device having a smaller size, and, particularly, a reduced height and reduced total device volume.
It is an object of the present invention to provide an implantable drug infusion device which reduces or wholly overcomes some or all of the difficulties inherent in prior known devices. Particular objects and advantages of the invention will be apparent to those skilled in the art, that is, those who are knowledgeable or experienced in this field of technology, in view of the following disclosure of the invention and detailed description of preferred embodiments.
The present invention provides an implantable drug infusion device which features a pumphead assembly and a motor assembly for driving the pumphead assembly in a new configuration, in which the pumphead and motor assembly are adjacent to, and laterally offset from, one another, thereby reducing the overall height of the device.
In accordance with a first aspect, an implantable drug infusion device includes a pumphead assembly having a drive shaft; and a motor assembly operably connected to the drive shaft. The motor assembly is adjacent the pumphead assembly in a radial direction with respect to the drive shaft.
In accordance with another aspect, an implantable drug infusion device includes a bulkhead having a race, a first chamber and a second chamber. A pump tube has an inlet and an outlet and is positioned within the race. A pumphead assembly has a drive shaft and is located within the first chamber. A motor assembly is located within the second chamber and is operably connected to the drive shaft of the pumphead assembly. The motor assembly is adjacent the pumphead assembly in a radial direction with respect to the drive shaft.
From the foregoing disclosure, it will be readily apparent to those skilled in the art, that is, those who are knowledgeable or experienced in this area of technology, that the present invention provides a significant advance over the prior art. Preferred embodiments of the implantable infusion device of the present invention can significantly reduce the overall height of the apparatus as compared to prior implantable pumps, and minimize discomfort to the patient. These and additional features and advantages of the invention disclosed here will be further understood from the following detailed disclosure of preferred embodiments.